<!DOCTYPE HTML>
<html lang="zh-CN">


<head>
    <meta charset="utf-8">
    <meta name="keywords" content="Set和Map, W.BOWEN&#39;s blog">
    <meta name="description" content="接受失败,但不选择放弃">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <meta name="renderer" content="webkit|ie-stand|ie-comp">
    <meta name="mobile-web-app-capable" content="yes">
    <meta name="format-detection" content="telephone=no">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
    <!-- Global site tag (gtag.js) - Google Analytics -->


    <title>Set和Map | W.BOWEN&#39;s blog</title>
    <link rel="icon" type="image/png" href="/wangbowen-hexo-blog/favicon.png">

    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/libs/awesome/css/all.css">
    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/libs/materialize/materialize.min.css">
    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/libs/aos/aos.css">
    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/libs/animate/animate.min.css">
    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/libs/lightGallery/css/lightgallery.min.css">
    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/css/matery.css">
    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/css/my.css">

    <script src="/wangbowen-hexo-blog/libs/jquery/jquery.min.js"></script>

<meta name="generator" content="Hexo 5.3.0"></head>




<body>
    <header class="navbar-fixed">
    <nav id="headNav" class="bg-color nav-transparent">
        <div id="navContainer" class="nav-wrapper container">
            <div class="brand-logo">
                <a href="/wangbowen-hexo-blog/" class="waves-effect waves-light">
                    
                    <img src="/wangbowen-hexo-blog/medias/logo.png" class="logo-img" alt="LOGO">
                    
                    <span class="logo-span">W.BOWEN&#39;s blog</span>
                </a>
            </div>
            

<a href="#" data-target="mobile-nav" class="sidenav-trigger button-collapse"><i class="fas fa-bars"></i></a>
<ul class="right nav-menu">
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/" class="waves-effect waves-light">
      
      <i class="fas fa-home" style="zoom: 0.6;"></i>
      
      <span>首页</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/tags" class="waves-effect waves-light">
      
      <i class="fas fa-tags" style="zoom: 0.6;"></i>
      
      <span>标签</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/categories" class="waves-effect waves-light">
      
      <i class="fas fa-bookmark" style="zoom: 0.6;"></i>
      
      <span>分类</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/archives" class="waves-effect waves-light">
      
      <i class="fas fa-archive" style="zoom: 0.6;"></i>
      
      <span>归档</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/about" class="waves-effect waves-light">
      
      <i class="fas fa-user-circle" style="zoom: 0.6;"></i>
      
      <span>关于</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/contact" class="waves-effect waves-light">
      
      <i class="fas fa-comments" style="zoom: 0.6;"></i>
      
      <span>留言板</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/wangbowen-hexo-blog/friends" class="waves-effect waves-light">
      
      <i class="fas fa-address-book" style="zoom: 0.6;"></i>
      
      <span>友情链接</span>
    </a>
    
  </li>
  
  <li>
    <a href="#searchModal" class="modal-trigger waves-effect waves-light">
      <i id="searchIcon" class="fas fa-search" title="搜索" style="zoom: 0.85;"></i>
    </a>
  </li>
</ul>


<div id="mobile-nav" class="side-nav sidenav">

    <div class="mobile-head bg-color">
        
        <img src="/wangbowen-hexo-blog/medias/logo.png" class="logo-img circle responsive-img">
        
        <div class="logo-name">W.BOWEN&#39;s blog</div>
        <div class="logo-desc">
            
            接受失败,但不选择放弃
            
        </div>
    </div>

    

    <ul class="menu-list mobile-menu-list">
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-home"></i>
			
			首页
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/tags" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-tags"></i>
			
			标签
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/categories" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-bookmark"></i>
			
			分类
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/archives" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-archive"></i>
			
			归档
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/about" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-user-circle"></i>
			
			关于
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/contact" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-comments"></i>
			
			留言板
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/wangbowen-hexo-blog/friends" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-address-book"></i>
			
			友情链接
		</a>
          
        </li>
        
        
        <li><div class="divider"></div></li>
        <li>
            <a href="https://gitee.com/wang-bowen" class="waves-effect waves-light" target="_blank">
                <i class="fab fa-github-square fa-fw"></i>Fork Me
            </a>
        </li>
        
    </ul>
</div>


        </div>

        
            <style>
    .nav-transparent .github-corner {
        display: none !important;
    }

    .github-corner {
        position: absolute;
        z-index: 10;
        top: 0;
        right: 0;
        border: 0;
        transform: scale(1.1);
    }

    .github-corner svg {
        color: #0f9d58;
        fill: #fff;
        height: 64px;
        width: 64px;
    }

    .github-corner:hover .octo-arm {
        animation: a 0.56s ease-in-out;
    }

    .github-corner .octo-arm {
        animation: none;
    }

    @keyframes a {
        0%,
        to {
            transform: rotate(0);
        }
        20%,
        60% {
            transform: rotate(-25deg);
        }
        40%,
        80% {
            transform: rotate(10deg);
        }
    }
</style>

<a href="https://gitee.com/wang-bowen" class="github-corner tooltipped hide-on-med-and-down" target="_blank"
   data-tooltip="Fork Me" data-position="left" data-delay="50">
    <svg viewBox="0 0 250 250" aria-hidden="true">
        <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
        <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
              fill="currentColor" style="transform-origin: 130px 106px;" class="octo-arm"></path>
        <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z"
              fill="currentColor" class="octo-body"></path>
    </svg>
</a>
        
    </nav>

</header>

    



<div class="bg-cover pd-header post-cover" style="background-image: url('/wangbowen-hexo-blog/medias/featureimages/6.jpg')">
    <div class="container" style="right: 0px;left: 0px;">
        <div class="row">
            <div class="col s12 m12 l12">
                <div class="brand">
                    <h1 class="description center-align post-title">Set和Map</h1>
                </div>
            </div>
        </div>
    </div>
</div>




<main class="post-container content">

    
    <link rel="stylesheet" href="/wangbowen-hexo-blog/libs/tocbot/tocbot.css">
<style>
    #articleContent h1::before,
    #articleContent h2::before,
    #articleContent h3::before,
    #articleContent h4::before,
    #articleContent h5::before,
    #articleContent h6::before {
        display: block;
        content: " ";
        height: 100px;
        margin-top: -100px;
        visibility: hidden;
    }

    #articleContent :focus {
        outline: none;
    }

    .toc-fixed {
        position: fixed;
        top: 64px;
    }

    .toc-widget {
        width: 345px;
        padding-left: 20px;
    }

    .toc-widget .toc-title {
        padding: 35px 0 15px 17px;
        font-size: 1.5rem;
        font-weight: bold;
        line-height: 1.5rem;
    }

    .toc-widget ol {
        padding: 0;
        list-style: none;
    }

    #toc-content {
        padding-bottom: 30px;
        overflow: auto;
    }

    #toc-content ol {
        padding-left: 10px;
    }

    #toc-content ol li {
        padding-left: 10px;
    }

    #toc-content .toc-link:hover {
        color: #42b983;
        font-weight: 700;
        text-decoration: underline;
    }

    #toc-content .toc-link::before {
        background-color: transparent;
        max-height: 25px;

        position: absolute;
        right: 23.5vw;
        display: block;
    }

    #toc-content .is-active-link {
        color: #42b983;
    }

    #floating-toc-btn {
        position: fixed;
        right: 15px;
        bottom: 76px;
        padding-top: 15px;
        margin-bottom: 0;
        z-index: 998;
    }

    #floating-toc-btn .btn-floating {
        width: 48px;
        height: 48px;
    }

    #floating-toc-btn .btn-floating i {
        line-height: 48px;
        font-size: 1.4rem;
    }
</style>
<div class="row">
    <div id="main-content" class="col s12 m12 l9">
        <!-- 文章内容详情 -->
<div id="artDetail">
    <div class="card">
        <div class="card-content article-info">
            <div class="row tag-cate">
                <div class="col s7">
                    
                    <div class="article-tag">
                        
                            <a href="/wangbowen-hexo-blog/tags/JavaScript/">
                                <span class="chip bg-color">JavaScript</span>
                            </a>
                        
                    </div>
                    
                </div>
                <div class="col s5 right-align">
                    
                </div>
            </div>

            <div class="post-info">
                
                <div class="post-date info-break-policy">
                    <i class="far fa-calendar-minus fa-fw"></i>发布日期:&nbsp;&nbsp;
                    2021-03-22
                </div>
                

                

                

                

                
            </div>
        </div>
        <hr class="clearfix">

        

        

        <div class="card-content article-card-content">
            <div id="articleContent">
                <h2 id="Set"><a href="#Set" class="headerlink" title="Set"></a>Set</h2><h3 id="基本用法"><a href="#基本用法" class="headerlink" title="基本用法"></a>基本用法</h3><p>ES6提供新的数据结构Set。它类似于数组,但是<strong>成员的值都是唯一的,没有重复的值</strong>。</p>
<p><code>Set</code>本身是一个构造函数,用来生成Set数据结构。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> s = <span class="keyword">new</span> <span class="built_in">Set</span>();</span><br><span class="line"></span><br><span class="line">[<span class="number">2</span>, <span class="number">3</span>, <span class="number">5</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">2</span>, <span class="number">2</span>].forEach(<span class="function"><span class="params">x</span> =&gt;</span> s.add(x));</span><br><span class="line"></span><br><span class="line"><span class="keyword">for</span>(<span class="keyword">let</span> i <span class="keyword">of</span> s) &#123;</span><br><span class="line">  <span class="built_in">console</span>.log(i); <span class="comment">// 2, 3, 5, 4</span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>上述代码通过<code>add()</code>方法向Set结构加入成员,结果表明<strong>Set结构不会添加重复的值</strong>。</p>
<p><code>Set函数</code>可以接收一个数组(或者具有iterable接口的其他数据结构)作为参数,用来初始化。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 一</span></span><br><span class="line"><span class="keyword">const</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">4</span>]);</span><br><span class="line"><span class="built_in">console</span>.log([...set]); <span class="comment">// [1, 2, 3, 4]</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 二</span></span><br><span class="line"><span class="keyword">const</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">5</span>]);</span><br><span class="line"><span class="built_in">console</span>.log(set.size) <span class="comment">// 5</span></span><br></pre></td></tr></table></figure>
<p><strong>Set可以用于去除数组重复成员的方法,也可以用于去除字符串里的重复字符。</strong></p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 去除数组重复成员</span></span><br><span class="line">[...new <span class="built_in">Set</span>(array)]</span><br><span class="line"><span class="comment">// 去除字符串重复字符</span></span><br><span class="line">[...new <span class="built_in">Set</span>(<span class="string">&quot;ababbc&quot;</span>).join(<span class="string">&quot;&quot;</span>)]; <span class="comment">// &quot;abc&quot;</span></span><br></pre></td></tr></table></figure>
<p>向Set加入值的时候,不会发生类型转换,所以<code>5</code>和<code>&quot;5&quot;</code>是两个不同的值。Set内部判断两个值是否不同,类似于全等运算符(<code>===</code>),主要的区别是向Set加入值时认为<code>NaN</code>等于自身,而全等运算符认为<code>NaN</code>不等于自身</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">let</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>();</span><br><span class="line"><span class="keyword">const</span> a = <span class="literal">NaN</span>;</span><br><span class="line"><span class="keyword">const</span> b = <span class="literal">NaN</span>;</span><br><span class="line">set.add(a).add(b);</span><br><span class="line"><span class="built_in">console</span>.log(set); <span class="comment">// Set(1) &#123;NaN&#125;</span></span><br></pre></td></tr></table></figure>
<p>代码向Set添加了两次<code>NaN</code>,但是只会加入一个,这表明,在Set内部两个<code>NaN</code>是相等的。另外,<strong>两个对象总不相等(因为引用地址不同)。</strong></p>
<h3 id="Set实例的属性和方法"><a href="#Set实例的属性和方法" class="headerlink" title="Set实例的属性和方法"></a>Set实例的属性和方法</h3><ol>
<li>Set结构的实例有以下属性。</li>
</ol>
<ul>
<li><code>Set.prototype.constructor</code>: 构造函数,默认就是<code>Set</code>函数。</li>
<li><code>Set.prototype.size</code>: 返回Set实例的成员个数。</li>
</ul>
<ol start="2">
<li>Set实例的方法分两大类: <code>操作方法</code>(用于操作数据)和<code>遍历方法</code>(用于遍历成员)</li>
</ol>
<ul>
<li><code>Set.prototype.add(value)</code>: 添加某个值,返回Set结构本身。(<strong>可串联多个add(),只能有一个参数,第二个及以后参数会被自动忽略。</strong>)</li>
<li><code>Set.prototype.delete(value)</code>: 删除某个值,返回布尔值,表示删除是否成功。</li>
<li><code>Set.prototype.has(value)</code>: 查询该值是否为<code>Set</code>的成员(值)。返回一个布尔值。</li>
<li><code>Set.prototype.clear()</code>: 清除所有成员,无返回值。</li>
</ul>
<p><code>Object</code>结构和<code>Set</code>结构的在判断是否包括在一个键上写法不同。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 对象写法</span></span><br><span class="line"><span class="keyword">const</span> properties = &#123;</span><br><span class="line">  width: <span class="number">1</span>,</span><br><span class="line">  height: <span class="number">1</span></span><br><span class="line">&#125;;</span><br><span class="line"><span class="keyword">if</span>(properties[someName]) &#123;&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// Set写法</span></span><br><span class="line"><span class="keyword">const</span> properties = <span class="keyword">new</span> <span class="built_in">Set</span>();</span><br><span class="line">properties.add(<span class="string">&quot;width&quot;</span>).add(<span class="string">&quot;height&quot;</span>);</span><br><span class="line"><span class="keyword">if</span>(properties.has(someName)) &#123;&#125;</span><br></pre></td></tr></table></figure>
<p><code>Array.from()</code>方法可以将Set结构转为数组,这就提供了另一种数组去重的方法。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">unique</span>(<span class="params">array</span>) </span>&#123;</span><br><span class="line">  <span class="keyword">return</span> <span class="built_in">Array</span>.from(<span class="keyword">new</span> <span class="built_in">Set</span>(array));</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">unique([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">3</span>]) <span class="comment">// [1, 2, 3]</span></span><br></pre></td></tr></table></figure>
<h3 id="遍历操作"><a href="#遍历操作" class="headerlink" title="遍历操作"></a>遍历操作</h3><ol>
<li>Set结构的实例有四个遍历方法,可以用于遍历成员。</li>
</ol>
<ul>
<li><code>Set.prototype.keys()</code>: 返回<code>键名</code>的遍历器。</li>
<li><code>Set.prototype.values()</code>: 返回<code>键值</code>的遍历器。</li>
<li><code>Set.prototype.entries()</code>: 返回<code>键值对</code>的遍历器。</li>
<li><code>Set.prototype.forEach()</code>: 使用回调函数遍历每个成员。</li>
</ul>
<p><strong><code>Set</code>的遍历顺序就是插入顺序。</strong></p>
<ol start="2">
<li><code>keys()</code>、<code>values()</code>、<code>entries()</code></li>
</ol>
<p><code>keys</code>方法、<code>values</code>方法、<code>entries</code>方法返回的都是遍历器对象。由于Set没有键名,只有键值,所以<code>keys</code>方法和<code>values</code>方法的行为完全一致。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="string">&quot;red&quot;</span>, <span class="string">&quot;green&quot;</span>, <span class="string">&quot;blue&quot;</span>]);</span><br><span class="line"></span><br><span class="line"><span class="keyword">for</span>(<span class="keyword">let</span> i <span class="keyword">of</span> set.keys()) &#123;</span><br><span class="line">  <span class="built_in">console</span>.log(i); <span class="comment">// red  green  blue</span></span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">for</span>(<span class="keyword">let</span> i <span class="keyword">of</span> set.values()) &#123;</span><br><span class="line">  <span class="built_in">console</span>.log(i) <span class="comment">// red  green  blue</span></span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">for</span>(<span class="keyword">let</span> i <span class="keyword">of</span> set.entries()) &#123;</span><br><span class="line">  <span class="built_in">console</span>.log(i) <span class="comment">// [&quot;red&quot;, &quot;red&quot;]  [&quot;green&quot;, &quot;green&quot;]  [&quot;blue&quot;, &quot;blue&quot;] </span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>上面代码中,<code>entries()方法</code>返回的遍历器,同时包括键名和键值,所以每次输出一个数组,它的两个成员完全相等。</p>
<p>Set结构的实例默认可遍历,它的默认遍历器生成函数就它的<code>values</code>方法。这就意味着,可以省略<code>values</code>方法,直接用<code>for...of</code>循环遍历Set。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="string">&quot;red&quot;</span>, <span class="string">&quot;green&quot;</span>, <span class="string">&quot;blue&quot;</span>]);</span><br><span class="line"><span class="keyword">for</span>(<span class="keyword">let</span> i <span class="keyword">of</span> set) &#123;</span><br><span class="line">  <span class="built_in">console</span>.log(i); <span class="comment">// red green blue</span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<ol start="3">
<li><code>forEach()</code></li>
</ol>
<ul>
<li>Set结构的实例与数组一样,也拥有<code>forEach</code>方法,用于对每个成员执行某种操作,没有返回值。</li>
<li>forEach方法的参数就是一个处理函数,该函数的参数与数组的<code>forEach</code>一致,依次为<code>键值</code>、<code>键名</code>、<code>集合本身</code>。因为Set结构的键名就是键值,因此第一个参数和第二个参数的值永远是一样的。</li>
</ul>
<ol start="4">
<li>遍历的应用</li>
</ol>
<ul>
<li>扩展运算符(<code>...</code>)内部使用<code>for...of</code>循环,所以也可以用于Set结构。</li>
<li>扩展运算符和Set结构结合,就可以去除数组的重复成员。<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> arr = [<span class="number">3</span>, <span class="number">5</span>, <span class="number">2</span>, <span class="number">2</span>, <span class="number">5</span>, <span class="number">4</span>];</span><br><span class="line"><span class="keyword">let</span> unique = [...new <span class="built_in">Set</span>(arr)];</span><br><span class="line"><span class="comment">// [3, 5, 2, 4]</span></span><br></pre></td></tr></table></figure></li>
<li>数组的<code>map</code>方法和<code>filter</code>方法也可以间接用于Set。<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">let</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);</span><br><span class="line">set = <span class="keyword">new</span> <span class="built_in">Set</span>([...set].map(<span class="function"><span class="params">x</span> =&gt;</span> x * <span class="number">2</span>));</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;2, 4, 6&#125;</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">let</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>]);</span><br><span class="line">set = <span class="keyword">new</span> <span class="built_in">Set</span>([...set].filter(<span class="function"><span class="params">item</span> =&gt;</span> (item % <span class="number">2</span>) == <span class="number">0</span>));</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;2, 4&#125;</span></span><br></pre></td></tr></table></figure></li>
<li>因此使用Set可以很容易的实现并集(Union)、交集(Intersect)和差集(Difference)。<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> a = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);</span><br><span class="line"><span class="keyword">const</span> b = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">4</span>, <span class="number">3</span>, <span class="number">2</span>]);</span><br><span class="line"></span><br><span class="line"><span class="comment">// 并集</span></span><br><span class="line"><span class="keyword">const</span> union = <span class="keyword">new</span> <span class="built_in">Set</span>([...a, ...b]);</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;1, 2, 3, 4&#125;</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 交集</span></span><br><span class="line"><span class="keyword">const</span> intersect = <span class="keyword">new</span> <span class="built_in">Set</span>([...a].filter(<span class="function"><span class="params">x</span> =&gt;</span> b.has(x)));</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;2, 3&#125;</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 差集</span></span><br><span class="line"><span class="keyword">const</span> difference = <span class="keyword">new</span> <span class="built_in">Set</span>([...a].filter(<span class="function"><span class="params">x</span> =&gt;</span> !b.has(x)));</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;1&#125;</span></span><br></pre></td></tr></table></figure></li>
<li>如果想在遍历操作中,同步改变原来的Set结构有两种方法:一种是利用原Set结构映射出一个新的结构,然后赋值给原来的Set结构;另一种是利用<code>Array.from()</code>方法</li>
<li><code>Array.from(array, mapFn, thisArg)</code>方法从一个类似数组或可迭代对象创建一个新的、浅拷贝的数组实例。<ol>
<li>第一个参数:想要转换成数组的伪数组对象或可迭代对象</li>
<li>第二个参数:可选,如果指定了该参数,新数组中的每个元素都会执行该回调函数。</li>
<li>第三个参数:可选,执行回调函数mapFn时的this对象。<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 方法一</span></span><br><span class="line"><span class="keyword">const</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);</span><br><span class="line">set = <span class="keyword">new</span> <span class="built_in">Set</span>([...set].map(<span class="function"><span class="params">x</span> =&gt;</span> x * <span class="number">2</span>));</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;2, 4, 6&#125;</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 方法二</span></span><br><span class="line"><span class="keyword">const</span> set = <span class="keyword">new</span> <span class="built_in">Set</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);</span><br><span class="line">set = <span class="keyword">new</span> <span class="built_in">Set</span>(<span class="built_in">Array</span>.from(set, <span class="function"><span class="params">x</span> =&gt;</span> x * <span class="number">2</span>));</span><br><span class="line"><span class="comment">// 返回Set结构: &#123;2, 4, 6&#125;</span></span><br></pre></td></tr></table></figure>
<h2 id="WeakSet"><a href="#WeakSet" class="headerlink" title="WeakSet"></a>WeakSet</h2></li>
</ol>
</li>
</ul>
<h3 id="含义"><a href="#含义" class="headerlink" title="含义"></a>含义</h3><p>WeakSet结构与Set类似,也是不重复的值的集合。但是,它与Set有两个区别</p>
<ol>
<li>WeakSet的成员只能是对象,而不能是其他类型的值</li>
</ol>
<p><a target="_blank" rel="noopener" href="https://imgtu.com/i/cQje3T"><img src="https://z3.ax1x.com/2021/04/05/cQje3T.png" alt="cQje3T.png"></a></p>
<ol start="2">
<li>WeakSet中的对象都是弱引用,即垃圾回收机制不考虑WeakSet对该对象的引用,也就是说,<strong>如果其他对象都不再引用该对象,那么垃圾回收机制会自动回收该对象所占用的内存,不考虑该对象是否还存在与WeakSet中</strong>。</li>
</ol>
<p>因为垃圾回收机制依赖引用计数,如果一个值的引用次数不为<code>0</code>,垃圾回收机制就不会释放这块内存。结束使用该值后,有时候忘记取消引用,可能引发内存泄漏问题。WeakSet里面的引用,都不计入垃圾回收机制,所以不存在这个问题。<strong>WeakSet适合临时存放一组对象,以及存放跟对象绑定的信息。只要这些对象在外部消失,它在WeakSet里的引用就会自动消失。</strong></p>
<p><strong>ES6规定WeakSet不可遍历。</strong></p>
<h3 id="语法"><a href="#语法" class="headerlink" title="语法"></a>语法</h3><p>WeakSet是一个构造函数,可以使用<code>new</code>,创建WeakSet数据结构。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> ws = <span class="keyword">new</span> <span class="built_in">WeakSet</span>();</span><br></pre></td></tr></table></figure>
<p>作为构造函数,WeakSet可以接收一个数组或或类似数组的对象作为参数。(<strong>任何具有Iterable接口的对象都可以作为WeakSet的参数</strong>)该数组的所有<code>成员</code>(而不是数组本身),都会自动成为WeakSet实例对象的<code>成员</code>。</p>
<p>WeakSet结构的三个方法:</p>
<ul>
<li><code>WeakSet.prototype.add(value</code>): 向WeakSet实例添加一个新成员。</li>
<li><code>WeakSet.prototype.delete(value)</code>: 清除WeakSet实例的<code>指定</code>成员。</li>
<li><code>WeakSet.prototype.has(value)</code>: 查询某个值是否在WeakSet实例之中。返回一个布尔值。</li>
</ul>
<p>WeakSet没有<code>size</code>属性,没有办法遍历它的成员。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> ws = <span class="keyword">new</span> <span class="built_in">WeakSet</span>();</span><br><span class="line"><span class="keyword">const</span> obj = &#123;&#125;;</span><br><span class="line"><span class="keyword">const</span> foo = &#123;&#125;;</span><br><span class="line"></span><br><span class="line">ws.add(<span class="built_in">window</span>).add(obj);</span><br><span class="line"></span><br><span class="line">ws.has(obj); <span class="comment">// true</span></span><br><span class="line">ws.has(foo); <span class="comment">//false</span></span><br><span class="line"></span><br><span class="line">ws.delete(<span class="built_in">window</span>);</span><br><span class="line">ws.has(<span class="built_in">window</span>); <span class="comment">// false</span></span><br><span class="line"></span><br><span class="line">ws.size <span class="comment">// undefined</span></span><br><span class="line">ws.forEach(<span class="function"><span class="params">item</span> =&gt;</span> <span class="built_in">console</span>.log(item)); <span class="comment">// Uncaught TypeError: ws.forEach is not a function</span></span><br></pre></td></tr></table></figure>
<p><strong>WeakSet不能遍历,是因为成员都是弱引用,随时都可能消失,遍历机制无法保证成员的存在。WeakSet的一个用处,是存储DOM节点,不用担心这些节点从文档移除时,引发内存泄漏。</strong></p>
<h2 id="Map"><a href="#Map" class="headerlink" title="Map"></a>Map</h2><h3 id="含义和基本用法"><a href="#含义和基本用法" class="headerlink" title="含义和基本用法"></a>含义和基本用法</h3><p>ES6提供的Map数据结构。类似于对象,也是键值对的集合,但是键名不限于字符串,各种类型的值(包括对象)都能当作键。</p>
<p>作为构造函数,<code>Map</code>也可以接收一个数组作为参数。该数组的成员是一个个表示键值对的数组。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>([</span><br><span class="line">  [<span class="string">&#x27;name&#x27;</span>,  <span class="string">&#x27;张三&#x27;</span>],</span><br><span class="line">  [<span class="string">&#x27;title&#x27;</span>, <span class="string">&#x27;Author&#x27;</span>]</span><br><span class="line">]);</span><br><span class="line">map.size; <span class="comment">// 2</span></span><br><span class="line">map.has(<span class="string">&#x27;name&#x27;</span>); <span class="comment">// true</span></span><br><span class="line">map.get(<span class="string">&#x27;name&#x27;</span>); <span class="comment">// 张三</span></span><br><span class="line">map.has(<span class="string">&#x27;title&#x27;</span>); <span class="comment">// true</span></span><br><span class="line">map.get(<span class="string">&#x27;title&#x27;</span>); <span class="comment">// Author</span></span><br></pre></td></tr></table></figure>
<p>实际上执行的是以下代码</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> items = [</span><br><span class="line">  [<span class="string">&#x27;name&#x27;</span>,  <span class="string">&#x27;张三&#x27;</span>],</span><br><span class="line">  [<span class="string">&#x27;title&#x27;</span>, <span class="string">&#x27;Author&#x27;</span>]</span><br><span class="line">];</span><br><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>();</span><br><span class="line"></span><br><span class="line">items.forEach(<span class="function">(<span class="params">item, index</span>) =&gt;</span> &#123;</span><br><span class="line">  map.set(item, index)</span><br><span class="line">&#125;);</span><br></pre></td></tr></table></figure>
<p>不仅仅是数组,任何具有Iterator接口、且每个成员都是一个双元素(例如: [‘a’, 1])的数组的数组结构都可以当作<code>Map</code>构造函数的参数(如果数组中只有一个元素,这个元素会被当作键名,键值为undefined)。这就是说,<code>Set</code>和<code>Map</code>都可以用来生成新的<code>Map</code>。</p>
<p><strong>如果对同一个键多次赋值,后面的值将覆盖前面的值。</strong></p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>();</span><br><span class="line"></span><br><span class="line">map.set(<span class="number">1</span>, <span class="string">&#x27;aaa&#x27;</span>)</span><br><span class="line">   .set(<span class="number">1</span>, <span class="string">&#x27;bbb&#x27;</span>);</span><br><span class="line"></span><br><span class="line">map.get(<span class="number">1</span>); <span class="comment">// bbb</span></span><br></pre></td></tr></table></figure>
<p>如果读取一个未知的键,则返回<code>undefined</code>。</p>
<p>只有对同一个对象的引用,Map结构才会将其视为同一个键。不同的对象引用地址不同。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>();</span><br><span class="line"></span><br><span class="line"><span class="keyword">const</span> k1 = [<span class="string">&#x27;a&#x27;</span>];</span><br><span class="line"><span class="keyword">const</span> k2 = [<span class="string">&#x27;a&#x27;</span>];</span><br><span class="line"></span><br><span class="line">map.set(k1, <span class="number">111</span>);</span><br><span class="line">map.set(k2, <span class="number">222</span>);</span><br><span class="line"></span><br><span class="line">map.get(k1); <span class="comment">// 111</span></span><br><span class="line">map.get(k2); <span class="comment">// 222</span></span><br></pre></td></tr></table></figure>
<p><code>Map</code>的键实际上是跟内存地址绑定的,只要内存地址不同,那么就视为两个键。<code>Map</code>解决了同名属性碰撞的问题。</p>
<p>如果Map的键是一个简单类型的值,则只要两个值<code>严格相等</code>,Map就会将其视为一个键,要注意的是,<code>undefined</code>和<code>null</code>是两个不同的键;两个<code>NaN</code>在Map中视为同一个键。</p>
<h3 id="实例的属性和操作方法"><a href="#实例的属性和操作方法" class="headerlink" title="实例的属性和操作方法"></a>实例的属性和操作方法</h3><ol>
<li>size属性</li>
</ol>
<p><code>size</code>属性返回Map结构的成员总数。</p>
<ol start="2">
<li>Map.prototype.set(key, value)</li>
</ol>
<p><code>set</code>方法设置键名<code>key</code>对应的键值为<code>value</code>,然后返回整个Map结构。如果<code>key</code>已经有值,则键值会被更新,否则就新生成该键。<code>set</code>可以采用链式编程的写法。(<strong>只能传key和value,如果有第三个及以后的参数Map会自动忽略。</strong>)</p>
<ol start="3">
<li>Map.prototype.get(key)</li>
</ol>
<p><code>get</code>方法读取<code>key</code>对应的键值,如果找不到<code>key</code>,返回<code>undefined</code>。</p>
<ol start="4">
<li>Map.prototype.has(key)</li>
</ol>
<p><code>has</code>方法返回一个布尔值,表示<code>某个键</code>是否在当前Map对象之中。</p>
<ol start="5">
<li>Map.prototype.delete(key)</li>
</ol>
<p><code>delete</code>方法删除某个键,返回<code>true</code>。如果删除失败返回<code>false</code>。</p>
<ol start="6">
<li>Map.prototype.clear()</li>
</ol>
<p><code>clear</code>方法清除所有成员,没有返回值。</p>
<h3 id="遍历方法"><a href="#遍历方法" class="headerlink" title="遍历方法"></a>遍历方法</h3><p>Map结构原生提供三个遍历器生成函数和一个遍历方法。</p>
<ul>
<li><code>Map.prototype.keys()</code>: 返回键名的遍历器</li>
<li><code>Map.prototype.values()</code>: 返回键值的遍历器</li>
<li><code>Map.prototype.entries()</code>: 返回键值对的遍历器,Map结构的默认遍历器接口(<code>Symbol.iterator属性</code>),就是<code>entries</code>方法。</li>
<li><code>Map.prototype.forEach()</code>: 遍历Map的所有成员</li>
</ul>
<p>Map的遍历顺序就是插入顺序:</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>([</span><br><span class="line">  [<span class="string">&quot;a&quot;</span>, <span class="string">&quot;no&quot;</span>],</span><br><span class="line">  [<span class="string">&quot;b&quot;</span>, <span class="string">&quot;yes&quot;</span>]</span><br><span class="line">]);</span><br><span class="line"></span><br><span class="line">map.keys(); <span class="comment">// MapIterator &#123;&quot;a&quot;, &quot;b&quot;&#125;</span></span><br><span class="line"></span><br><span class="line">map.values(); <span class="comment">// MapIterator &#123;&quot;no&quot;, &quot;yes&quot;&#125;</span></span><br><span class="line"></span><br><span class="line">map.entries(); <span class="comment">// MapIterator &#123;&quot;F&quot; =&gt; &quot;no&quot;, &quot;T&quot; =&gt; &quot;yes&quot;&#125;</span></span><br><span class="line"></span><br></pre></td></tr></table></figure>
<p>Map结构转为数组结构,比较快速的方法是使用扩展运算符(<code>...</code>)。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>([</span><br><span class="line">  [<span class="number">1</span>, <span class="string">&#x27;one&#x27;</span>],</span><br><span class="line">  [<span class="number">2</span>, <span class="string">&#x27;two&#x27;</span>],</span><br><span class="line">  [<span class="number">3</span>, <span class="string">&#x27;three&#x27;</span>],</span><br><span class="line">])</span><br><span class="line"></span><br><span class="line">[...map.keys()] <span class="comment">// [1, 2, 3]</span></span><br><span class="line"></span><br><span class="line">[...map.values()] <span class="comment">// [&#x27;one&#x27;, &#x27;two&#x27;, &#x27;three&#x27;]</span></span><br><span class="line"></span><br><span class="line">[...map.entries()] <span class="comment">// [ [1,&#x27;one&#x27;], [2, &#x27;two&#x27;], [3, &#x27;three&#x27;] ]</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 因为map.entries()是默认的遍历器接口,可以直接写成</span></span><br><span class="line">[...map]</span><br><span class="line"></span><br></pre></td></tr></table></figure>
<p>结合数组的<code>map</code>方法、<code>filter</code>方法,可以实现Map的遍历和过滤(Map本身没有<code>map</code>和<code>filter</code>方法)。</p>
<h3 id="与其他数据结构的相互转换"><a href="#与其他数据结构的相互转换" class="headerlink" title="与其他数据结构的相互转换"></a>与其他数据结构的相互转换</h3><ol>
<li>Map转为数组</li>
</ol>
<p>Map转为数组最方便的方法,就是使用扩展运算符(<code>...</code>)。</p>
<ol start="2">
<li>数组转为Map</li>
</ol>
<p>将数组传入Map构造函数,就可以转为Map。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>([</span><br><span class="line">  [<span class="literal">true</span>, <span class="number">7</span>],</span><br><span class="line">  [&#123;<span class="string">&quot;foo&quot;</span>, <span class="number">3</span>&#125;, [<span class="string">&quot;abc&quot;</span>]]</span><br><span class="line">])</span><br><span class="line"></span><br><span class="line"><span class="comment">// Map &#123;</span></span><br><span class="line"><span class="comment">//   true =&gt; 7,</span></span><br><span class="line"><span class="comment">//   Object &#123;foo: 3&#125; =&gt; [&quot;abc&quot;]</span></span><br><span class="line"><span class="comment">// &#125;</span></span><br></pre></td></tr></table></figure>
<ol start="3">
<li>Map转为对象</li>
</ol>
<p>如果所有的Map的键都是字符串,它可以无损的转为对象。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">mapToObj</span>(<span class="params">map</span>) </span>&#123;</span><br><span class="line">  <span class="comment">// 创建一个没有任何属性的对象</span></span><br><span class="line">  <span class="keyword">let</span> obj = <span class="built_in">Object</span>.create(<span class="literal">null</span>);</span><br><span class="line">  <span class="keyword">for</span>(<span class="keyword">let</span> [key, value] <span class="keyword">of</span> map) &#123;</span><br><span class="line">    obj[key] = value;</span><br><span class="line">  &#125;</span><br><span class="line">  <span class="keyword">return</span> obj;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">const</span> myMap = <span class="keyword">new</span> <span class="built_in">Map</span>().set(<span class="string">&#x27;yes&#x27;</span>, <span class="literal">true</span>).set(<span class="string">&#x27;no&#x27;</span>, <span class="literal">false</span>);</span><br><span class="line"><span class="comment">// 或者可写成const myMap = new Map([ [&#x27;yes&#x27;, true], [&#x27;no&#x27;, false] ]);</span></span><br><span class="line"></span><br><span class="line">mapToObj(myMap); <span class="comment">// &#123; yes: true, no: false &#125;</span></span><br></pre></td></tr></table></figure>
<ol start="4">
<li>对象转为Map</li>
</ol>
<p>对象转为Map可以通过<code>Object.entries(obj)</code>,该方法返回一个给定对象自身<code>可枚举属性</code>的键值对数组。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">let</span> obj = &#123; <span class="attr">a</span>: <span class="number">1</span>, <span class="attr">b</span>: <span class="number">2</span> &#125;;</span><br><span class="line"><span class="keyword">let</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>(<span class="built_in">Object</span>.entries(obj));</span><br></pre></td></tr></table></figure>
<p>或者可以通过<code>Object.keys(obj)</code>,该方法返回一个给定对象自身<code>可枚举属性</code>组成的数组。</p>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">objToMap</span>(<span class="params">obj</span>) </span>&#123;</span><br><span class="line">  <span class="keyword">let</span> map = <span class="keyword">new</span> <span class="built_in">Map</span>();</span><br><span class="line">  <span class="keyword">for</span>(<span class="keyword">let</span> key <span class="keyword">of</span> <span class="built_in">Object</span>.keys(obj)) &#123;</span><br><span class="line">    map.set(key, obj[key]);</span><br><span class="line">  &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">objToMap(&#123; <span class="attr">yes</span>: <span class="literal">true</span>, <span class="attr">no</span>: <span class="literal">false</span> &#125;); </span><br><span class="line"><span class="comment">// Map &#123;&quot;yes&quot; =&gt; true, &quot;no&quot; =&gt; false&#125; </span></span><br></pre></td></tr></table></figure>
<h2 id="WeakMap"><a href="#WeakMap" class="headerlink" title="WeakMap"></a>WeakMap</h2><h3 id="含义-1"><a href="#含义-1" class="headerlink" title="含义"></a>含义</h3><p><code>WeakMap</code>结构与<code>Map</code>结构类似,也是用于生成键值对的集合。<code>WeakMap</code>与<code>Map</code>的区别有两点:</p>
<ul>
<li><code>WeakMap</code>只接收对象作为键名(<code>null</code>除外),不接受其他类型的值作为键名。<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> wm = <span class="keyword">new</span> <span class="built_in">WeakMap</span>();</span><br><span class="line"></span><br><span class="line"><span class="comment">// Uncaught TypeError: Invalid value used as weak map key.</span></span><br><span class="line">map.set(<span class="literal">null</span>, <span class="number">2</span>);</span><br></pre></td></tr></table></figure></li>
<li><code>WeakMap</code>的键名所指向的对象,不计入垃圾回收机制。</li>
</ul>
<p><code>WeakMap</code>设计目的在于,有时候想在某个对象上存放一些数据,但是会形成对于这个对象的引用。一旦不再需要该对象,就必须手动删除这个引用(<code>null赋值</code>)。否则会导致内存泄漏问题。</p>
<p>WeakMap的键名所引用的对象都是弱引用,即垃圾回收机制不将该引用考虑在内。所有,只要所引用的对象的其他引用被清除,垃圾回收机制就会释放该对象所占用的内存。也就是说,WeakMap里面的键名对象和所对应的键值对会自动消失,不用手动删除引用。</p>
<h3 id="WeakMap的语法"><a href="#WeakMap的语法" class="headerlink" title="WeakMap的语法"></a>WeakMap的语法</h3><p>WeakMap与Map在API的区别主要是两个,一是没有遍历操作(即没有<code>keys()</code>、<code>values()</code>、<code>entries()</code>方法),也没有<code>size</code>属性。因为没有办法列出所有键名,跟垃圾回收机制是否运行相关。为了防止出现不确定性,就统一规定不能取到键名。二是无法清空,即不支持<code>clear</code>方法。因此,WeakMap只有四个方法可用: <code>get()</code>、<code>set()</code>、<code>has()</code>、<code>delete()</code>。</p>

                
            </div>
            <hr/>

            

    <div class="reprint" id="reprint-statement">
        
            <div class="reprint__author">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-user">
                        文章作者:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="/wangbowen-hexo-blog/about" rel="external nofollow noreferrer">W.BOWEN</a>
                </span>
            </div>
            <div class="reprint__type">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-link">
                        文章链接:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="https://gitee.com/wang-bowen0629/wangbowen-hexo-blog/2021/03/22/set-he-map/">https://gitee.com/wang-bowen0629/wangbowen-hexo-blog/2021/03/22/set-he-map/</a>
                </span>
            </div>
            <div class="reprint__notice">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-copyright">
                        版权声明:
                    </i>
                </span>
                <span class="reprint-info">
                    本博客所有文章除特別声明外，均采用
                    <a href="https://creativecommons.org/licenses/by/4.0/deed.zh" rel="external nofollow noreferrer" target="_blank">CC BY 4.0</a>
                    许可协议。转载请注明来源
                    <a href="/wangbowen-hexo-blog/about" target="_blank">W.BOWEN</a>
                    !
                </span>
            </div>
        
    </div>

    <script async defer>
      document.addEventListener("copy", function (e) {
        let toastHTML = '<span>复制成功，请遵循本文的转载规则</span><button class="btn-flat toast-action" onclick="navToReprintStatement()" style="font-size: smaller">查看</a>';
        M.toast({html: toastHTML})
      });

      function navToReprintStatement() {
        $("html, body").animate({scrollTop: $("#reprint-statement").offset().top - 80}, 800);
      }
    </script>



            <div class="tag_share" style="display: block;">
                <div class="post-meta__tag-list" style="display: inline-block;">
                    
                        <div class="article-tag">
                            
                                <a href="/wangbowen-hexo-blog/tags/JavaScript/">
                                    <span class="chip bg-color">JavaScript</span>
                                </a>
                            
                        </div>
                    
                </div>
                <div class="post_share" style="zoom: 80%; width: fit-content; display: inline-block; float: right; margin: -0.15rem 0;">
                    <link rel="stylesheet" type="text/css" href="/wangbowen-hexo-blog/libs/share/css/share.min.css">
<div id="article-share">

    
    <div class="social-share" data-sites="twitter,facebook,google,qq,qzone,wechat,weibo,douban,linkedin" data-wechat-qrcode-helper="<p>微信扫一扫即可分享！</p>"></div>
    <script src="/wangbowen-hexo-blog/libs/share/js/social-share.min.js"></script>
    

    

</div>

                </div>
            </div>
            
                <style>
    #reward {
        margin: 40px 0;
        text-align: center;
    }

    #reward .reward-link {
        font-size: 1.4rem;
        line-height: 38px;
    }

    #reward .btn-floating:hover {
        box-shadow: 0 6px 12px rgba(0, 0, 0, 0.2), 0 5px 15px rgba(0, 0, 0, 0.2);
    }

    #rewardModal {
        width: 320px;
        height: 350px;
    }

    #rewardModal .reward-title {
        margin: 15px auto;
        padding-bottom: 5px;
    }

    #rewardModal .modal-content {
        padding: 10px;
    }

    #rewardModal .close {
        position: absolute;
        right: 15px;
        top: 15px;
        color: rgba(0, 0, 0, 0.5);
        font-size: 1.3rem;
        line-height: 20px;
        cursor: pointer;
    }

    #rewardModal .close:hover {
        color: #ef5350;
        transform: scale(1.3);
        -moz-transform:scale(1.3);
        -webkit-transform:scale(1.3);
        -o-transform:scale(1.3);
    }

    #rewardModal .reward-tabs {
        margin: 0 auto;
        width: 210px;
    }

    .reward-tabs .tabs {
        height: 38px;
        margin: 10px auto;
        padding-left: 0;
    }

    .reward-content ul {
        padding-left: 0 !important;
    }

    .reward-tabs .tabs .tab {
        height: 38px;
        line-height: 38px;
    }

    .reward-tabs .tab a {
        color: #fff;
        background-color: #ccc;
    }

    .reward-tabs .tab a:hover {
        background-color: #ccc;
        color: #fff;
    }

    .reward-tabs .wechat-tab .active {
        color: #fff !important;
        background-color: #22AB38 !important;
    }

    .reward-tabs .alipay-tab .active {
        color: #fff !important;
        background-color: #019FE8 !important;
    }

    .reward-tabs .reward-img {
        width: 210px;
        height: 210px;
    }
</style>

<div id="reward">
    <a href="#rewardModal" class="reward-link modal-trigger btn-floating btn-medium waves-effect waves-light red">赏</a>

    <!-- Modal Structure -->
    <div id="rewardModal" class="modal">
        <div class="modal-content">
            <a class="close modal-close"><i class="fas fa-times"></i></a>
            <h4 class="reward-title">你的赏识是我前进的动力</h4>
            <div class="reward-content">
                <div class="reward-tabs">
                    <ul class="tabs row">
                        <li class="tab col s6 alipay-tab waves-effect waves-light"><a href="#alipay">支付宝</a></li>
                        <li class="tab col s6 wechat-tab waves-effect waves-light"><a href="#wechat">微 信</a></li>
                    </ul>
                    <div id="alipay">
                        <img src="/wangbowen-hexo-blog/medias/reward/alipay.jpg" class="reward-img" alt="支付宝打赏二维码">
                    </div>
                    <div id="wechat">
                        <img src="/wangbowen-hexo-blog/medias/reward/wechat.png" class="reward-img" alt="微信打赏二维码">
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>

<script>
    $(function () {
        $('.tabs').tabs();
    });
</script>

            
        </div>
    </div>

    

    

    

    

    
        <style>
    .valine-card {
        margin: 1.5rem auto;
    }

    .valine-card .card-content {
        padding: 20px 20px 5px 20px;
    }

    #vcomments textarea {
        box-sizing: border-box;
        background: url("/wangbowen-hexo-blog/medias/comment_bg.png") 100% 100% no-repeat;
    }

    #vcomments p {
        margin: 2px 2px 10px;
        font-size: 1.05rem;
        line-height: 1.78rem;
    }

    #vcomments blockquote p {
        text-indent: 0.2rem;
    }

    #vcomments a {
        padding: 0 2px;
        color: #4cbf30;
        font-weight: 500;
        text-decoration: none;
    }

    #vcomments img {
        max-width: 100%;
        height: auto;
        cursor: pointer;
    }

    #vcomments ol li {
        list-style-type: decimal;
    }

    #vcomments ol,
    ul {
        display: block;
        padding-left: 2em;
        word-spacing: 0.05rem;
    }

    #vcomments ul li,
    ol li {
        display: list-item;
        line-height: 1.8rem;
        font-size: 1rem;
    }

    #vcomments ul li {
        list-style-type: disc;
    }

    #vcomments ul ul li {
        list-style-type: circle;
    }

    #vcomments table, th, td {
        padding: 12px 13px;
        border: 1px solid #dfe2e5;
    }

    #vcomments table, th, td {
        border: 0;
    }

    table tr:nth-child(2n), thead {
        background-color: #fafafa;
    }

    #vcomments table th {
        background-color: #f2f2f2;
        min-width: 80px;
    }

    #vcomments table td {
        min-width: 80px;
    }

    #vcomments h1 {
        font-size: 1.85rem;
        font-weight: bold;
        line-height: 2.2rem;
    }

    #vcomments h2 {
        font-size: 1.65rem;
        font-weight: bold;
        line-height: 1.9rem;
    }

    #vcomments h3 {
        font-size: 1.45rem;
        font-weight: bold;
        line-height: 1.7rem;
    }

    #vcomments h4 {
        font-size: 1.25rem;
        font-weight: bold;
        line-height: 1.5rem;
    }

    #vcomments h5 {
        font-size: 1.1rem;
        font-weight: bold;
        line-height: 1.4rem;
    }

    #vcomments h6 {
        font-size: 1rem;
        line-height: 1.3rem;
    }

    #vcomments p {
        font-size: 1rem;
        line-height: 1.5rem;
    }

    #vcomments hr {
        margin: 12px 0;
        border: 0;
        border-top: 1px solid #ccc;
    }

    #vcomments blockquote {
        margin: 15px 0;
        border-left: 5px solid #42b983;
        padding: 1rem 0.8rem 0.3rem 0.8rem;
        color: #666;
        background-color: rgba(66, 185, 131, .1);
    }

    #vcomments pre {
        font-family: monospace, monospace;
        padding: 1.2em;
        margin: .5em 0;
        background: #272822;
        overflow: auto;
        border-radius: 0.3em;
        tab-size: 4;
    }

    #vcomments code {
        font-family: monospace, monospace;
        padding: 1px 3px;
        font-size: 0.92rem;
        color: #e96900;
        background-color: #f8f8f8;
        border-radius: 2px;
    }

    #vcomments pre code {
        font-family: monospace, monospace;
        padding: 0;
        color: #e8eaf6;
        background-color: #272822;
    }

    #vcomments pre[class*="language-"] {
        padding: 1.2em;
        margin: .5em 0;
    }

    #vcomments code[class*="language-"],
    pre[class*="language-"] {
        color: #e8eaf6;
    }

    #vcomments [type="checkbox"]:not(:checked), [type="checkbox"]:checked {
        position: inherit;
        margin-left: -1.3rem;
        margin-right: 0.4rem;
        margin-top: -1px;
        vertical-align: middle;
        left: unset;
        visibility: visible;
    }

    #vcomments b,
    strong {
        font-weight: bold;
    }

    #vcomments dfn {
        font-style: italic;
    }

    #vcomments small {
        font-size: 85%;
    }

    #vcomments cite {
        font-style: normal;
    }

    #vcomments mark {
        background-color: #fcf8e3;
        padding: .2em;
    }

    #vcomments table, th, td {
        padding: 12px 13px;
        border: 1px solid #dfe2e5;
    }

    table tr:nth-child(2n), thead {
        background-color: #fafafa;
    }

    #vcomments table th {
        background-color: #f2f2f2;
        min-width: 80px;
    }

    #vcomments table td {
        min-width: 80px;
    }

    #vcomments [type="checkbox"]:not(:checked), [type="checkbox"]:checked {
        position: inherit;
        margin-left: -1.3rem;
        margin-right: 0.4rem;
        margin-top: -1px;
        vertical-align: middle;
        left: unset;
        visibility: visible;
    }
</style>

<div class="card valine-card" data-aos="fade-up">
    <div class="comment_headling" style="font-size: 20px; font-weight: 700; position: relative; padding-left: 20px; top: 15px; padding-bottom: 5px;">
        <i class="fas fa-comments fa-fw" aria-hidden="true"></i>
        <span>评论</span>
    </div>
    <div id="vcomments" class="card-content" style="display: grid">
    </div>
</div>

<script src="/wangbowen-hexo-blog/libs/valine/av-min.js"></script>
<script src="/wangbowen-hexo-blog/libs/valine/Valine.min.js"></script>
<script>
    new Valine({
        el: '#vcomments',
        appId: 'EDT5zRbrzUXInYp7SCupHY7m-gzGzoHsz',
        appKey: 'u9CyC9PTy66xmdnLhq7Hu8PX',
        notify: 'true' === 'true',
        verify: 'true' === 'true',
        visitor: 'true' === 'true',
        avatar: 'mm',
        pageSize: '10',
        lang: 'zh-cn',
        placeholder: '有好的建议请留言八！'
    });
</script>

<!--酷Q推送-->


    

    

    

    

    

<article id="prenext-posts" class="prev-next articles">
    <div class="row article-row">
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge left-badge text-color">
                <i class="fas fa-chevron-left"></i>&nbsp;上一篇</div>
            <div class="card">
                <a href="/wangbowen-hexo-blog/2021/04/12/es6-shu-zu-xin-yu-fa/">
                    <div class="card-image">
                        
                        
                        <img src="/wangbowen-hexo-blog/medias/featureimages/15.jpg" class="responsive-img" alt="数组的一些方法...">
                        
                        <span class="card-title">数组的一些方法...</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            
                        
                    </div>
                    <div class="publish-info">
                        <span class="publish-date">
                            <i class="far fa-clock fa-fw icon-date"></i>2021-04-12
                        </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-user fa-fw"></i>
                            W.BOWEN
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/wangbowen-hexo-blog/tags/JavaScript/">
                        <span class="chip bg-color">JavaScript</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge right-badge text-color">
                下一篇&nbsp;<i class="fas fa-chevron-right"></i>
            </div>
            <div class="card">
                <a href="/wangbowen-hexo-blog/2021/03/02/xing-neng-you-hua/">
                    <div class="card-image">
                        
                        
                        <img src="/wangbowen-hexo-blog/medias/featureimages/2.jpg" class="responsive-img" alt="性能优化琐碎">
                        
                        <span class="card-title">性能优化琐碎</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            
                        
                    </div>
                    <div class="publish-info">
                            <span class="publish-date">
                                <i class="far fa-clock fa-fw icon-date"></i>2021-03-02
                            </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-user fa-fw"></i>
                            W.BOWEN
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/wangbowen-hexo-blog/tags/%E6%80%A7%E8%83%BD%E4%BC%98%E5%8C%96/">
                        <span class="chip bg-color">性能优化</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
    </div>
</article>

</div>



<!-- 代码块功能依赖 -->
<script type="text/javascript" src="/wangbowen-hexo-blog/libs/codeBlock/codeBlockFuction.js"></script>

<!-- 代码语言 -->

<script type="text/javascript" src="/wangbowen-hexo-blog/libs/codeBlock/codeLang.js"></script>


<!-- 代码块复制 -->

<script type="text/javascript" src="/wangbowen-hexo-blog/libs/codeBlock/codeCopy.js"></script>


<!-- 代码块收缩 -->

<script type="text/javascript" src="/wangbowen-hexo-blog/libs/codeBlock/codeShrink.js"></script>


    </div>
    <div id="toc-aside" class="expanded col l3 hide-on-med-and-down">
        <div class="toc-widget card" style="background-color: white;">
            <div class="toc-title"><i class="far fa-list-alt"></i>&nbsp;&nbsp;目录</div>
            <div id="toc-content"></div>
        </div>
    </div>
</div>

<!-- TOC 悬浮按钮. -->

<div id="floating-toc-btn" class="hide-on-med-and-down">
    <a class="btn-floating btn-large bg-color">
        <i class="fas fa-list-ul"></i>
    </a>
</div>


<script src="/wangbowen-hexo-blog/libs/tocbot/tocbot.min.js"></script>
<script>
    $(function () {
        tocbot.init({
            tocSelector: '#toc-content',
            contentSelector: '#articleContent',
            headingsOffset: -($(window).height() * 0.4 - 45),
            collapseDepth: Number('0'),
            headingSelector: 'h2, h3, h4'
        });

        // modify the toc link href to support Chinese.
        let i = 0;
        let tocHeading = 'toc-heading-';
        $('#toc-content a').each(function () {
            $(this).attr('href', '#' + tocHeading + (++i));
        });

        // modify the heading title id to support Chinese.
        i = 0;
        $('#articleContent').children('h2, h3, h4').each(function () {
            $(this).attr('id', tocHeading + (++i));
        });

        // Set scroll toc fixed.
        let tocHeight = parseInt($(window).height() * 0.4 - 64);
        let $tocWidget = $('.toc-widget');
        $(window).scroll(function () {
            let scroll = $(window).scrollTop();
            /* add post toc fixed. */
            if (scroll > tocHeight) {
                $tocWidget.addClass('toc-fixed');
            } else {
                $tocWidget.removeClass('toc-fixed');
            }
        });

        
        /* 修复文章卡片 div 的宽度. */
        let fixPostCardWidth = function (srcId, targetId) {
            let srcDiv = $('#' + srcId);
            if (srcDiv.length === 0) {
                return;
            }

            let w = srcDiv.width();
            if (w >= 450) {
                w = w + 21;
            } else if (w >= 350 && w < 450) {
                w = w + 18;
            } else if (w >= 300 && w < 350) {
                w = w + 16;
            } else {
                w = w + 14;
            }
            $('#' + targetId).width(w);
        };

        // 切换TOC目录展开收缩的相关操作.
        const expandedClass = 'expanded';
        let $tocAside = $('#toc-aside');
        let $mainContent = $('#main-content');
        $('#floating-toc-btn .btn-floating').click(function () {
            if ($tocAside.hasClass(expandedClass)) {
                $tocAside.removeClass(expandedClass).hide();
                $mainContent.removeClass('l9');
            } else {
                $tocAside.addClass(expandedClass).show();
                $mainContent.addClass('l9');
            }
            fixPostCardWidth('artDetail', 'prenext-posts');
        });
        
    });
</script>

    

</main>




    <footer class="page-footer bg-color">
    
        <link rel="stylesheet" href="/wangbowen-hexo-blog/libs/aplayer/APlayer.min.css">
<style>
    .aplayer .aplayer-lrc p {
        
        display: none;
        
        font-size: 12px;
        font-weight: 700;
        line-height: 16px !important;
    }

    .aplayer .aplayer-lrc p.aplayer-lrc-current {
        
        display: none;
        
        font-size: 15px;
        color: #42b983;
    }

    
    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body {
        left: -66px !important;
    }

    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body:hover {
        left: 0px !important;
    }

    
</style>
<div class="">
    
    <div class="row">
        <meting-js class="col l8 offset-l2 m10 offset-m1 s12"
                   server="netease"
                   type="playlist"
                   id="503838841"
                   fixed='true'
                   autoplay='true'
                   theme='#42b983'
                   loop='all'
                   order='random'
                   preload='auto'
                   volume='0.7'
                   list-folded='true'
        >
        </meting-js>
    </div>
</div>

<script src="/wangbowen-hexo-blog/libs/aplayer/APlayer.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/meting@2/dist/Meting.min.js"></script>

    
    <div class="container row center-align" style="margin-bottom: 0px !important;">
        <div class="col s12 m8 l8 copy-right">
            Copyright&nbsp;&copy;
            
                <span id="year">2019-2024</span>
            
            <span id="year">2019</span>
            <a href="/wangbowen-hexo-blog/about" target="_blank">W.BOWEN</a>
            |&nbsp;Powered by&nbsp;<a href="https://hexo.io/" target="_blank">Hexo</a>
            |&nbsp;Theme&nbsp;<a href="https://github.com/blinkfox/hexo-theme-matery" target="_blank">Matery</a>
            <br>
            
            
            
            
            
            
            <span id="busuanzi_container_site_pv">
                |&nbsp;<i class="far fa-eye"></i>&nbsp;总访问量:&nbsp;<span id="busuanzi_value_site_pv"
                    class="white-color"></span>&nbsp;次
            </span>
            
            
            <span id="busuanzi_container_site_uv">
                |&nbsp;<i class="fas fa-users"></i>&nbsp;总访问人数:&nbsp;<span id="busuanzi_value_site_uv"
                    class="white-color"></span>&nbsp;人
            </span>
            
            <br>
            
            <br>
            
        </div>
        <div class="col s12 m4 l4 social-link social-statis">
    <a href="https://gitee.com/wang-bowen" class="tooltipped" target="_blank" data-tooltip="访问我的GitHub" data-position="top" data-delay="50">
        <i class="fab fa-github"></i>
    </a>



    <a href="mailto:784801819@qq.com" class="tooltipped" target="_blank" data-tooltip="邮件联系我" data-position="top" data-delay="50">
        <i class="fas fa-envelope-open"></i>
    </a>







    <a href="tencent://AddContact/?fromId=50&fromSubId=1&subcmd=all&uin=784801819" class="tooltipped" target="_blank" data-tooltip="QQ联系我: 784801819" data-position="top" data-delay="50">
        <i class="fab fa-qq"></i>
    </a>







    <a href="/wangbowen-hexo-blog/atom.xml" class="tooltipped" target="_blank" data-tooltip="RSS 订阅" data-position="top" data-delay="50">
        <i class="fas fa-rss"></i>
    </a>

</div>
    </div>
</footer>

<div class="progress-bar"></div>


    <!-- 搜索遮罩框 -->
<div id="searchModal" class="modal">
    <div class="modal-content">
        <div class="search-header">
            <span class="title"><i class="fas fa-search"></i>&nbsp;&nbsp;搜索</span>
            <input type="search" id="searchInput" name="s" placeholder="请输入搜索的关键字"
                   class="search-input">
        </div>
        <div id="searchResult"></div>
    </div>
</div>

<script type="text/javascript">
$(function () {
    var searchFunc = function (path, search_id, content_id) {
        'use strict';
        $.ajax({
            url: path,
            dataType: "xml",
            success: function (xmlResponse) {
                // get the contents from search data
                var datas = $("entry", xmlResponse).map(function () {
                    return {
                        title: $("title", this).text(),
                        content: $("content", this).text(),
                        url: $("url", this).text()
                    };
                }).get();
                var $input = document.getElementById(search_id);
                var $resultContent = document.getElementById(content_id);
                $input.addEventListener('input', function () {
                    var str = '<ul class=\"search-result-list\">';
                    var keywords = this.value.trim().toLowerCase().split(/[\s\-]+/);
                    $resultContent.innerHTML = "";
                    if (this.value.trim().length <= 0) {
                        return;
                    }
                    // perform local searching
                    datas.forEach(function (data) {
                        var isMatch = true;
                        var data_title = data.title.trim().toLowerCase();
                        var data_content = data.content.trim().replace(/<[^>]+>/g, "").toLowerCase();
                        var data_url = data.url;
                        data_url = data_url.indexOf('/') === 0 ? data.url : '/' + data_url;
                        var index_title = -1;
                        var index_content = -1;
                        var first_occur = -1;
                        // only match artiles with not empty titles and contents
                        if (data_title !== '' && data_content !== '') {
                            keywords.forEach(function (keyword, i) {
                                index_title = data_title.indexOf(keyword);
                                index_content = data_content.indexOf(keyword);
                                if (index_title < 0 && index_content < 0) {
                                    isMatch = false;
                                } else {
                                    if (index_content < 0) {
                                        index_content = 0;
                                    }
                                    if (i === 0) {
                                        first_occur = index_content;
                                    }
                                }
                            });
                        }
                        // show search results
                        if (isMatch) {
                            str += "<li><a href='" + data_url + "' class='search-result-title'>" + data_title + "</a>";
                            var content = data.content.trim().replace(/<[^>]+>/g, "");
                            if (first_occur >= 0) {
                                // cut out 100 characters
                                var start = first_occur - 20;
                                var end = first_occur + 80;
                                if (start < 0) {
                                    start = 0;
                                }
                                if (start === 0) {
                                    end = 100;
                                }
                                if (end > content.length) {
                                    end = content.length;
                                }
                                var match_content = content.substr(start, end);
                                // highlight all keywords
                                keywords.forEach(function (keyword) {
                                    var regS = new RegExp(keyword, "gi");
                                    match_content = match_content.replace(regS, "<em class=\"search-keyword\">" + keyword + "</em>");
                                });

                                str += "<p class=\"search-result\">" + match_content + "...</p>"
                            }
                            str += "</li>";
                        }
                    });
                    str += "</ul>";
                    $resultContent.innerHTML = str;
                });
            }
        });
    };

    searchFunc('/wangbowen-hexo-blog/search.xml', 'searchInput', 'searchResult');
});
</script>

    <!-- 回到顶部按钮 -->
<div id="backTop" class="top-scroll">
    <a class="btn-floating btn-large waves-effect waves-light" href="#!">
        <i class="fas fa-arrow-up"></i>
    </a>
</div>


    <script src="/wangbowen-hexo-blog/libs/materialize/materialize.min.js"></script>
    <script src="/wangbowen-hexo-blog/libs/masonry/masonry.pkgd.min.js"></script>
    <script src="/wangbowen-hexo-blog/libs/aos/aos.js"></script>
    <script src="/wangbowen-hexo-blog/libs/scrollprogress/scrollProgress.min.js"></script>
    <script src="/wangbowen-hexo-blog/libs/lightGallery/js/lightgallery-all.min.js"></script>
    <script src="/wangbowen-hexo-blog/js/matery.js"></script>

    <!-- Baidu Analytics -->

    <!-- Baidu Push -->

<script>
    (function () {
        var bp = document.createElement('script');
        var curProtocol = window.location.protocol.split(':')[0];
        if (curProtocol === 'https') {
            bp.src = 'https://zz.bdstatic.com/linksubmit/push.js';
        } else {
            bp.src = 'http://push.zhanzhang.baidu.com/push.js';
        }
        var s = document.getElementsByTagName("script")[0];
        s.parentNode.insertBefore(bp, s);
    })();
</script>

    
    <script src="/wangbowen-hexo-blog/libs/others/clicklove.js" async="async"></script>
    
    
    <script async src="/wangbowen-hexo-blog/libs/others/busuanzi.pure.mini.js"></script>
    

    

    

    <!--腾讯兔小巢-->
    
    

    

    

    
    <script src="/wangbowen-hexo-blog/libs/instantpage/instantpage.js" type="module"></script>
    

<script src="/wangbowen-hexo-blog/live2dw/lib/L2Dwidget.min.js?094cbace49a39548bed64abff5988b05"></script><script>L2Dwidget.init({"pluginRootPath":"live2dw/","pluginJsPath":"lib/","pluginModelPath":"assets/","tagMode":false,"debug":false,"model":{"jsonPath":"live2d-widget-model-z16"},"display":{"position":"right","width":200,"height":400},"mobile":{"show":false},"log":false});</script></body>

</html>
